Low-Voltage Detection Or Over-Voltage Detection - Daikin FTXS20K2V1B Service Manual

Troubleshooting
4.7

Low-voltage Detection or Over-voltage Detection

U2
Error Code
Method of Error
Detection
The zero-cross detection of the power supply is evaluated by the indoor unit PCB.
Low-voltage detection:
An abnormal voltage drop is detected by the DC voltage detection circuit.
Over-voltage detection:
An abnormal voltage rise is detected by the over-voltage detection circuit.
Error Decision
Conditions
There is no zero-cross detection in about 10 seconds.
Low-voltage detection:
Over-voltage detection:
Supposed
Causes
68
Indoor Unit
Outdoor Unit
Indoor Unit
Outdoor Unit
The voltage detected by the DC voltage detection circuit is below 180 V.
The compressor stops if the error occurs, and restarts automatically after 3-minute standby.
An over-voltage signal is fed from the over-voltage detection circuit to the microcomputer.
The compressor stops if the error occurs, and restarts automatically after 3-minute standby.
Power supply voltage is not as specified.
Defective DC voltage detection circuit
Defective over-voltage detection circuit
Defective PAM control part
Disconnection of compressor harness
Short circuit inside the fan motor winding
Noise
Momentary drop of voltage
Momentary power failure
Defective outdoor unit PCB
Defective indoor unit PCB
SiBE041134EB
Service Diagnosis